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I did research on this stuff back in the 1990s. Made the films, did the vacuum chambers, had the world record for emission efficiency for a while. While it may have some niche applications, the basic problem is that it is *not* a low-voltage technology. Modern chips operate on 1.5 V or so; Diamond devices will be more like 5V. So ultra-low power? Nope. They say that the devices are more efficient because the electrons don't bump their way through the silicon crystal lattice. While that's true enough, it doesn't actually make a big difference. Why? Because the electrons very much will dump all their energy when they leave the vacuum and hit the anode.

Ultra-high speed? Again, while vacuum is nice in that it doesn't slow down the electrons, that turns out not to be a big effect. The most important factor in speed is the size of the device, and there is certainly no reason to believe that these vacuum tubes will be smaller than transistors, if built with the same lithography tools. I may be wrong, but I have good reasons to believe that they will be harder to make small.

High temperature? Radiation resistance? Maybe, but that turns out to be a complex question. These devices aren't just diamond and vacuum. They involve insulating layers, too, and those insulators may be affected my high temperatures or radiation. Essentially, a device is as robust as its weakest link, so until you can make the entire device out of truly robust materials, you won't gain too much.

So, it's nice work. I know how hard it is to do this stuff. And, it might be useful eventually. But it won't revolutionize technology any time soon. And, those guys ought to realize that, if they would let themselves. Research lives off publicity these days, because it is being forced to become more and more of a competition between groups. The trouble is, when competition enters and your salary depends on the claims you can make, truth tends to be (shall we say) over-inflated.

That darn free market ideology messes up science. I like it as much as anything for people who make spoons or telephones. But science isn't making spoons. If you get a bad spoon, you'll know it, but if you read an exaggerated research paper, how can you tell, other than by doing the research again? And, that's just not efficient: doing it wrong and then doing it again isn't nearly as good as doing it right the first time.

The first semiconductor transistors were large enough to handle a single one with your hand. What makes you assume that the nanodiamond transistors cannot get smaller?

There are unfortuantly some additional physics problems that need to be address for miniturization of this technology.

One issue is the free-space electron transport. With silicon technology, the "channel" is doped silicon which carried the electrons (like a wire). The channel sort of acts like a waveguide for the electrons as the travel between the source and the drain (assuming common mos technology). In "free-space" transport between the cathode and anode (vacuum tube and the proposed nano-diamond transistor), you need to keep some sort of physical separation (in an all-free-space design) or some sort of electrical isolation betweeen devices (shielding).

The second issue is the structure. In the proposed diamond design, the diamond "circuitry" is patterned so that it is essentially carved to have structures above the silicon dioxide surface (as opposed to standard patterning which is either directly on the surface ion implated into the substrate). This nano-tech like structure will of course need to scale to get better. If they can take anything from the current silicon technology, shrinking in 2D (patterning) is much easier than shrinking in 3D (needed for reduced gate thickness needed to improve gate channel efficiency). In advanced silicon technology, 3D scaling has be all but abandoned in favor of techniques like tri-gate/fin-fet...

Note that I'm not saying these advances aren't possible, but they do not leverage any current manufacturing techniques, so it's likely that this stuff will be in the lab for a while whilst current technology will advance. When it does become feasible, it may or may not be competitive. This is not unlike ferro-magnetic ram might replace dram someday, or how solid state memories will replace rotating disk memory someday... Maybe someday, but it's equally possible that day may also never come or be so far out that other new technologies may gain a foothold (e.g., how RRAM might actual displace FRAM as the DRAM successor)...

As a silly example, if you invested the same amount of "area" in some farady-cage-like shielding of present day CML (current-mode-logic) technology electronics, would this nano-diamond technology be much better? I dunno, but these new-fangled technologies need to beat these kind of tweaks of current day technology to win. But of course we have to both try to do new things and try to improve old things and see which one comes out on top. However to assume that the appropriate technological and manufacturing advances will necessarily come to pass to make a general approach viable would be a mistake as a heap load of abandoned technologies will certainly attest to...